Answer:
is this your only question?
First, we pay attention to the numerical coefficients of the terms in the series: 10, 21, 32, 43, 54, 65. Conclusively they form an arithmetic sequence with a common difference of 11. Thus, the next numerical coefficient is 76. Then, we pay attention to the letters which are just arrange alphabetically. The next letter ought to be G which needs to be capitalized. Thus, the answer is letter C. 76G.
Use the distance formula?
A = L * W
A = 80
L = 5W
80 = W(5W)
80 = 5W^2
80/5 = W^2
16 = W^2
sqrt 16 = W
4 = W <=== width is 4 ft
L = 5W
L = 5(4)
L = 20 <=== length is 20 ft